Process for clearing clayey ores.



E. F. GOLTRA, T. S. MAFFIIT, J. D..DANA & R. W. ERWIN. PROCESS FORCLEARING CLAYEY ORES.

APPLICATION FILED JAN. 5. I914. 1L.3@11.@4 Patented Apr. 22,1919.

4 SHEETS-SHEET I.

E. F. GOLTRA. T. S. MAFFITT, J. D. DANA & R. W. ERWIN.

PROCESS FOR CLEARING CLAYEY OHES. APPLICATION FILED JAN. 5. 1914. lmfimh Patented Apr. 22, 1919.

4 SHEETS-SHEET 2.

LSQLGSU E. F. GOLTRA T. S. IVI'AFFITT, J. 'D. DANA'& R. W. ERWIN.PROCESS FOR CLEARING CLAYEY ones.

Patented Apr. 22, 1919.

APPLICATION FILED JAN- 5. WM.

4 SHEETSSHEET 3.

E. F. GOLTRA, T. S. MAFFIIT, J. D. DANA & R. W. ERWIN, PROCESS FORCLEARING CLAYEY OHES.

I APPLICATION FILED JANI5. I914. 1 m1 84k Patented Apr. 22, 1919.

4 SHEETSSHEET 4.

I I I I v onrrn snares rarnnar clarion.

I EDWARD I. G-OLTM THOMAS S. MAFFITT, D JESSE D. DANA, 015 ST. LOUIS,MISSOURI,

AND ROBERT W. ERWIN, 0F WAUKON, IOWA, ASSIGNDRS, BY MESNE ASSIGNMENTS,T0 MISSISSIPPI VALLEY IRON COMPANY, OF WILMINGTON, DELAWARE, A CORPO-RATION OF DELAWARE.

raocnss FOR CLEARING- CLAYEY onus.

Specificationjof Letters Patent.

Application field January 5, 1914i. Serial Ito. 810,530.

To all whom it may concern: 7

'Be it known that we, EDWARD F. GoL'rRA,

THoMAs S. MAFFITT, JESSE D. DANA, and ROBERT W. ERWIN, citizens of theUnited States, and residing at St. Louis, State of Missouri, and Waukon,Iowa, respectively, have invented new and useful Improvements inProcesses for Clearing Clayey Ores, of which the following is aspecification.

This invention relates to processes or methods for clearing ore of itsgangue, and more particularly to a process for clearing ores containingclay as a gangue.

Some ores, such as brown hematite and certain ores of copper, contain alarge percentage of clay and sometimes silica as a gangue. These oresexist as nodulesand boulders of various sizes in the clay beds, and theclay and silica, such as flint, stone.

gravel and sand, is often found inside of the lumps or bouldersf Nowthis gangue must be separated from the ore before it can be usedeconomically in a blast furnace. 4

In U. S. Patents Nos. 957,157, granted May 3, 1910, and 961,121, grantedJune 14, 1910, are described a process for clearing such clayey ore ofits gangue. The process as described in said patents may be brieflysummed up as follows: The ore and its gangue are heated at a.temperature and for a period sufficient to render the gangue brittle andeasily separable from the ore; the ore and its gangue are tumbled toshake loose the gangue from the ore, and the ore and gangue aresubjected to a strong air blast so as to sweep, clean and remove thegangue from the ore.

While the air cleanin process of said patents produces a mere antableore well suited for a blast furnace, and while this air cleaning processwill free the ore of substantially all of its clay gangue, it will notseparate the rock, flint, gravel and sand from the ore to a sufficientextent. As stated above, this silica occurs in combination with clay asa gangue, and often occurs inside of the lnnips or boulders of ore.

One of the objects of this invention there fore is to refine the processdescribed and claimed in the above patents so as to render it moreetlicient, so as to clear the ore of all various ores havingcharacteristics permitting its utilization, more particularly variousores containing clay as a gangue and occurrlng 1n the form of nodules inthe clay, and containing considerable moisture both free and combined.

Further objects will appear from the detail description, and indescribing the process reference Wlll be had to the accompany ingdrawings showing one form of apparatus for carrying out the process. Inthese drawings,

Figure 1 is a diagrammatical plan view of an apparatus illustrating theprocess embodying this invention,

Fig.2 is a profile or elevation also in diagrammatical form,

Fig. 3 is an enlarged diagrammatical detail profile or elevation,

Fig. 4 is another enlarged diagrammatical detai profile or elevationshowing the second converter, I

Fig. 5 is a plan showing the third converter,

Fig. 6 is a profile or side elevation, partly in section, of this thirdconverter,

Fig. 7 is a detail end elevation, showing the outlet door,

Fig. 8 is a. detail end elevation of the inlet end,

Fig. 9 is a section on the line 9 9 Fig. 8,

Fig. 10 is an enlarged detail section on the line 99 Fig. 8, and

Fig. 11 is an enlarged detail section on the line 11-11 Fig. 9.

The apparatus generally stated consists of three converters designatedgenerally by A,

one-third ofits length from its lower end Patented Apr. 22, 1919 withfire brick or other suitable material, while the unlined part has aseries of inwardly projecting shelves or lifters extending therealong.The upper end of the cylinder projects into a stationary hopper casing16 connectin with a hopper 17, which hopper receives the ore fromstationary grids 18 which in turn receive the ore from the mine. Thegrids are spaced any suitable distance so as to allow the ore below acertain size to pass therethrough; thus in this particular instancethese grids are spaced from 12 to 14 inches.

inches apart so as to allow everything under 14 inches to pass into thehop-per 17. This hopper is provided with two hinged valve plates 20 and21 placed in series to prevent the gases in the converter from enteringthe hopper. The casing 16 is connected with a stack 22 through a fan 23driven by a motor 24. This fan will cause a draft from the lower to theupper end of the cylinder and up the stack 22. The lower end of thecylinder projects into a. casing 25 which is provided with rolls so asto be movable longitudinally of the cylinder along a track 26, to allowfor expansion and contraction of the cylinder. A pulverized coal burner27 receives the coal from a. bin 28 and an air blast from a fan or pump29, and this coal is blown in a pulverized condition into the lower endof the cylinder 10. The cylinder is provided with a toothed ring 30meshing with a pinion 31 driven by a suitable motor.

The ore is dicharged from the cylinder 10 on shaking or reciprocatinggrids 35, which in this particular case discharge everything below 2=}inches into a chute 36, while the oversize discharges into a crusher 37,which maybe of the gyratory type, and which crusher reduces the materialto 2% The chute 36 from the reciprocaiting grids, and the. chute 38 fromthe crusher discharge into an elevator 39, which elevates the materialand discharges it into a sizing screen or t rom'mel 40. This trommelsizes the material in this particular instance to three sizes. The finematerial passes by achute 41 to a tailings bin 42, the second sizedmaterial passes by a. chute 43 to a belt conveyer 44, discharging intothe ore bin 45 and the oversize or coarse material passes onto a pickingbelt 46 where it is hand-picked and the picked ore discharged onto t 1econveyer 44 and hence taken to the ore bin 45'. The hopper 47 for thetailings bin 42 extends upwardly underneath the belt 46 so as to receivethe flint, etc., picked from the belt. s

The material from the bin 45 is taken to the second converter B which isshown in detail and enlarged in Fig. 4. This second converter is ofsubstantially the same construction as the first converter- A and isoperated in substantially the same manner. It consists in thisparticular instance. of an inclined cylinder 50 about 125 feet long and8 feet in diameter. It is however lined for a little over three-fourthsof its length from its lower end with fire brick or the like, while theunlined part is provided with inwardly projecting shelves extendingtherealong. This cylinder is supported by rings 51 on rolls 52 and 520on pillars 53 and 54. The center set of ring 51 and rolls 520 in thiscase also form a thrust bearing. The upper end of the cylinder extendsinto a casing 56 which is connected to an exhaust fan 57 discharginginto a dust collector 58 and from there into a stack 69. This dustcollector may be of any suitable. form and may be provided with inclinedshelves 59 placed in staggered relation so as to separate the dust fromthe air before it is discharged into the stack. An outlet 60 is providedfor this dust collector. A conveyer 61 conveys the ore from the bin 45to the casing56 and hence to the cylinder 50, The lower end of'thecylinder projects into a casing 62 provided with rolls and adjustablelengthwise of the cylinder along a track 63. A pulverized coal burner 64receives coal from a bin '65 and air from a blower or pump 66, and thisburner blows the pulverized coal into the lower end of the cylinder. Thecylinder is provided with a toothed ring 67 meshing with a pinion 68driven by a suitable motor.

The material as it leaves the second converter is taken by an elevator70 to a sizing trommel 71 which in this case sizes the ore to two sizes.The oversize is taken by a conveyer 72 and discharged onto a pickingbelt 73 where the flint etc. are hand-picked, while the picked ore isdischarged into the bin 74. The ore on the conveyer 72 is subjected to awater spray 75 so as to cool down the material before it reaches thepicking belt 73.

The undersize from the trommel 71 is discharged into a hopper. 76 andinto the third converter C which will now be de-' scribed. Referringmore particularly to Figs. 5 to 11 inclusive, which show the thirdconverter in detail, 77 designates a cylinder of boiler iron providedwith rings 78 resting on rolls 79 on pillars 80, and having a centerthrust ring 81 coiiperating wit-bl thrust rolls 82. This cylinder isprovided with a toothed ring 83 meshing with a pinion 84 driven by asuitable motor. The cylinder for about one-half of its length from itsupper end is of a comparatively large diameter, while the lower end isreduced as shown at 85 so as to form a comparatively long outlet ofsmall diameter. Thus in a practical case, the cylinder is 60 feet long,has a large diameter of 6% feet and a small diameter of 3%. feet.

The upper end of the cylinder makes an.

airtight connection with an end plate 35.?236

morass supported on a bracket 87, the end connection beingmade by a ring88 on a reduced extension 89 of the cylinder pressed by springs 90against the end plate 86. .The hopper 76 discharges through double valvecasings 91 and 92, and a chute 93 extending through the plate 86, intothe cylinder 77. The valve casings 91 and 92 are provided with valves 94and 95 respectively, suspended by links 98 from levers 97 pivoted on thehopper casings. These levers are pivoted in the valve casings by sleeves99 making close fits withbearing lugs 100 of the" valve casings so as tomake these joints air-tight. The levers 97 are provided with weights101. Links 102 are pivoted at their lower ends to the arms 97 and areprovided at their upper ends with elongated slots engaging cranks 103 ona shaft 104, which is driven from any suitable source of power.

A pipe 105 projects into the cylinder and extends just'through thebottom wall of the chute 93. This pipe 105 delivers crude oil under apressure of about 150 lbs. .per square inch from a tank 106.

The lower end of the cylinder 77 is closed by a door 107 pivoted at itsupper end to the frame 108 and held closed by strong springs 109. Thedoor 107 has a cut out portion 110 in which is pivoted a small door 111closed by weaker springs 112. Both doors bear against the end of thecylinder so as to form an airtight joint, but the lower door 111 isopened by the material passing out the cylinder, the opening beinghowever only sufidcient to permit the ore to; pass out. The function ofthe double door is that of a safety device, for

if an explosion takes place both doors will blow open and thereforefurnish a large outlet for the exploded gases and thereby prevent damageto the converter.

A conveyor 115 takes the material from the third converter to a sizingtrommel 116.

which sizes the material to a series of sizes so that it pan beconveniently operated upon by magnetic separators, The material on theconveyer 115 is passed underneath sprays 114 of cold water to quench thesame.

The material from the sizingtrommel is conveyed to magnetic'separatorsindicated at 117. These magnetic separators separate the ore from thegangue, the ore being conveyedto a suitable ore bin such as 74 and thetailings discarded.

The coal is stored in a bin 120 from whence it is conveyed to a drier121. From the drier the coal is taken by conveyers 122 and 123 to bins28 and respectively. in the diagrams, 124. designates the power houseand 125 and 126 designate tracks.

The operation will now be described, and in this operation we will takeas a practical case, for the material operated upon, limouite or brownhematite containing a large the converter is maintained at about 2200F., while the stack temperature, or the temperature at the upper end ofthe converter,

is maintained at about the boiling point of Water. The exhaustfancreates a draft of about one-half ounce. A low pressure current ofair is thus passed through the drum,

the air entering both with the pulverizedcoal and through the outletpassage in the casing 25. The material in passing through the firstconverter is subjected to a drying heat, and the operation performed inthis first converter is therefore a drying operation, whereby thematerial is freed of substantially all of its free moisture. During 1tspassage through the converter the ore and gangue, including the heavyboulders, which are as large as 14 inches, are lifted and tumbledaround, and during this tumbling operation the heavy boulders will breakup to some extent and break and disintegrate the ore and gangue, so thata crushing operation is performed in this converter, Simultaneously themassot ore and gangue is subjected to a gradually increasingtemperature, as the temperature increases from the upper to the lowerend oi? the converter, and this ore and gangue will therefore begradually dried out. This combined drying and tumbling operation willalso render the ore friable, and will in addition separate, 1'. 6.,shake loose some of the clay and other gangue, including the largerstone, mixed with the clay. lit will be noted however that while a draftof air is passed through the cylinder of this lirst converter, the blastis not a strong blast, for its function is merely a drying function; itsfunction is not primarily to carr off any or" the gangue, although someof t 1e clay which has become free and very finely powdered will beincidentall I carried oh by the 7 draft. The ore as it is ischarged fromthe first converter is at about 250 F, and this from the rest by atrommel, as hereinafter described.

The ore and gangue as discharged from the first converter is passed overthe shaking grids 35 which pass everything below 2%- inches into theelevator 39, while the oversize is sent to the crusher 37 and crusheddown to 2J inches, and discharged into the elevator 39. and gangue tothe sizing tronnnel 40 which sizes the material in three sizes asfollows: one-sixteenth inch and below, one-sixteenth inch tothree-fourths inch, and three-fourths inch and over. It is found thatthe one-sixteenth and below consists mostly of sand and clay and is verylean in ore. This size is therefore discharged directly into thetailings bin 42. The one-sixteenth to threefourths is dischargeddirectly into the ore bin 4.5 by means of the conveyer belt 44. Thethree-fourths and over is discharged onto a picking 'belt 16 where theflint, etc., are hand-picked, the picked ore passing into the ore bin.The purpose of the sizing between the second and third sizes is tofacilitate the hand picking, as it is found that most of the rock, flintand other siliceous material freed from the ore will be found in thissize. This sizing of the ore therefore first, discards the fines,consisting mostly of sand and clay and containig very little ore, andsecond, throws onlythe larger sizes on the picking belt where the flint,.etc., may be readily hand-picked and discarded.

The material is taken from the ore bin 45 to the second converter B.This second converter is driven at such a speed, and the incline issuch, that the material will pass through this converter in about 45minutes. The flame temperature maintained at the lower end of thisconverter is about 3200 l while the temperature at the upper end is from400 to 500 F. The exhaust fan in this case creates a strong blastthrough the converter cylinder of about 1-} ounces, which blast willlift particles of sand onesixteenth of an inch in diameter. As thematerial passes through the converter it is tumbled around, and at thesame time subjected to the .hot strong blast passing through theconverter. The temperature in this case also increases from the u per tothe lower end of the converter cylin er, but

' this temperature is very much higher than in the first converter. Asthe ore passes along the converter cylinder it will be subjected to acalcining heat which not only drives off any free moisture which may bepresent, but also drives ofi the combined moisture. The high temperaturecauses the ore and any associated siliceous gangue to cxpand unequallyand thus break open the lumps and expose this gangue. As the ore is thustumbled around and subjected to the This elevator takes the ore reorcetheat, the gangue will be loosened by the heat and shaken loose by thetumbling action, and dried out so as to become very brittle, and thisgangue is powdered by the tumbling action of the lumps against oneanother. This gangue so loosened and powdered will be picked up by thestrong blast passing through the converter and carried along with it,while the ore will continue downwardly toward the discharge end. Thegangue will not only be shaken loose from the surface of the ore, butwill also be shaken out of the cracks and crevices in and around theore, and this gangue will be separated from the ore by the strong blast.The blast will also seek out the gangue in the cracks and crevices andseparate it from the ore lumps, so that when the ore reaches thedischarge end of the converter it Will be freed of all of its claygangue. It will therefore be seen that after the ore leaves theconverter it will not only be entirely freed from its clay gangue, butalso from all of its free and combined moisture, so that the ore will bein a dry and porous condition, brought about by the cleaning out of thegangue and the expulsion of the combined moisture. Furthermore thecracking of the ore lumps and the tumbling will free the siliceousgangue from the ore, so that while this siliceous gangue may not all beseparated from the ore by the air blast, it will be loosened therefromto enable it to be separated in the subsequent operation hereinafter tobe described. The ore as it leaves the second converteris at a cherryred heat, or at about 1300 F.

The ore as discharged from the second converter is sized in a sizingtrommel to two sizes, an undersize of one-half inch and less,

and an oversize of one-half inch and over.v

therefore be conveniently and economically hand-picked, second, it isfound that the subsequent magnetizing process and the subsequentmagnetic separation can be performed more effectively if performed on anundersize of one-half inch and less, although we have found that themagnetizing and magnetic separation can be performed on pieces whichwill pass through a one inch mesh. The oversize is cooled down by spraysof water 75 and then discharged on a picking belt 73 where the ore ishand-picked.

The undersize from the sizing troinmel 71 is passed directly to thethird converter C. This third converter is made as airtight as possibleto prevent the entrance of outside air. The material is fed by thedouble valves, which exclude outside air, since these valves are sooperated that one will be always closcd while the other is open. En-

converter B is at about 1300 F, and as disore. ore sliding down over theend of the ipe to aoaeea trance of air during the feeding of the ore istherefore prevented. A gaseous hydrocarbon atmosphere is maintained byfeeding in crude oil under 150 lbs. pressure, and this oil is fed indirectly under the ore bed as it slides down the chute into theconverter cylinder, so as to mix directly with the hot This constructionwill also cause the keep the outlet clean and free. he oil forced intothe converter cylinder will volatilize and form a dense and concentratedhydrocarbon atmosphere in the cylinder. The upper end of the cylinder isof large diameter so as to furnish a large volume for the hydrocarbongases to act on the material. The lower end of the cylinder, or ratherthe lower half, is reduced in diameter so as to form a small outlet,thereby preventing entrance of air. The swinging doors at the lower endof the converter cylinder will also keep out the air, and the large dooris normally held closed while the lower or small door only opens to letout the material. The material as it is discharged from the secondcharged into the third converter C is at 1000 F. or over. The materialis therefore maintained in the third converter at about 1000 F. and over900 F., as it has been found that the temperature in this converter mustbe over 900 F. in order that the desired action may take place. Thematerial is kept in the third converter C for 30 minutes or over. It hasbeen found when treatedv as described, the ore as it leaves theconyerter is magnetic, a. e., it is attracted by a magnet. The materialas it leaves the converter is taken by a conveyer to a sizing trommel116, and while being conveyed is subjected to the action of jets ofwater to cool the same. The material is sized to meet the varyinrequirements of magnetic sep aration an is then separated magnetically.The material can be separated at as high a temperature as the magneticseparators will take it, but it will be found that it can be separatedcold.

The ore as it comes from the mine is limonite or brown hematite, that.is, hydrated sesquioxid of iron, 2Fe,0,,3H,O. The ore as it leaves thefirst converter has all its free moisture extracted but will have verylittle if any of the combined moisture taken out. The combined moistureis taken out of the ore during its age through the successive drying,crushing and calcining. The action of the hydrocarbon gases on the orein the third converter, at the high temperature there maintained,results in all probability, in a reduction of the sesquioxid to theferroso-ferric oxid, or from Fe O to Fe,,0,, or lFe O Fe(), and possiblylower oxids such as the protoxid or monoxid of iron,.that is Fe(). Theaction, may however be in part a physical change, and the magnetizationmay be in part due to a phyiscal change.

The magnetizing process embodies five salient features which distinguishit from prior processes. and which render it oommercially available.

First. The ore is sub-divided to an extent suflicient to permit thereducing gas to penetrate into the piece of ore, so as to reducepractically the entire mass thereof to Fe O and possibly lower oxids. Tnthe prior methods no particular attention was paid to this matter ofsub-division. As a result the ore was not reduced to an extentsutiicient to permit its separation by the mag netic separators. Itseems there was formed only a film or surface effect and any combinedmoisture left in the ore probably had an effect of oxidizing the reducedlayer of F 0,0, and FeO back to Fe,@,. It will be noted that in theprior processes the ore if reduced in size at all was reduced or crushedafter it left the reducing kiln. The result was therefore, that apartfrom any oxidizing action taking place after the ore left the kiln. inthe crushing, the interior of the lumps would be left. non-magnetizedand would not. of course." separate out in the magnetic separator. Thisis probably what caused the ineflicient magnetic separation of the oresas magnetized by the prior processes.

Second. It seems that the critical temperature at which the reducingaction takes place is about 900 F. lln accordance with this method theten'iperature is carried to over 900 F., and is usually about 1000. Ithas been found that when the temperature is dropped below 900 thereducing action is very inefficient. gives no permanent mag netization.and is commercially a failure.

Third. In accordance with this method a hydrocarbon gas is used which isrich in carbon, and more particularly in hydro en. The reducing actionof this gas is therefore more eiiicient than if a gas is used which isnot so rich in carbon and contains no or practically no hydrogen. Thusin the processes of the prior art where blast furnace gases. producergases and coke were used in a kiln, these gases contained practically nohydrogen and the reducin action of these gases was therefore not sucient for this ore. It will also be noted that in the proc esses of theprior art the gases were necessarily dilute and contained largequantities of nitrogen. Now in order to obtain an efficient reducingaction the gases must be rich and concentrated. This is the case withthe present process where hydrocarbon used, which is rich in both carbonand hydrogen. Hydrogen is one of the strongest reducing agents which canbe employed. Now the splitting of the hydrocarbons results in hydrogenbeing set free, and that this takes place is evidenced by the carboncoating on the ore as it leaves the third converter.

Fourth. In the processes of the prior art the gases necessarilycontained considerable free oxygen. Now in the reducing of the ore it isnecessary to maintain an atmosphere containing no oxygen, and it hasbeen found that unless the air is kept-out the reducing action is notonly inefficient but fails. Air not only causes oxidation but dilutesthe gas. In the present process the air is carefully excluded so that nooxidation or dilution of the hydrocarbon gases can take place.

Fifth. In accordance with this process both the free and combinedmoisture are driven off prior to subjecting the ore to the action of themagnetizing reagent. If the moisture, and more especlally the combinedmoisture is not driven ofi', then the magnetization will not alone beincomplete, but will not be permanent, since a reoxidation .may takeplace due to the presence of this combined moisture, as pointed outabove. Moreover the porosity of the ore not only permits a betterpenetration of the gases,

but also results in a more permanent magnetizing action.

While we have advanced an explanation and .theory to explain the actiontaking place, we do not however desire to be understood as advancingthis theory as the only one, or as being which may be advanced from theresults actually obtained by practical and commercial operation of theprocess.

Wh1le We have described only one particular apparatus for carrying outthis process, it will be obvious that this method may be carried out byapparatus other than described. It will further be obvious that whilethis process is particularly suitable for clayey iron ores, thisprocess, and more especially some of its features, may be utilized withother ores having. characteristics to permit the utilization of thisprocess. It is therefore to be understood that this invention is not tobe limited to the details shown and described.

The apparatus is fully described and claimed in our application, SerialNumber 810,531, filed of even date herewith, while the magnetizationprocess per 86 is fully dc scnbed and claimed 1n an application ofnecessary, but merely one RobertW. Erwin, Serial Number 810,532, filedof even date herewith.

Having thus described the invention what is claimed is:

1. The process of clearing ores having iron as an economic component,having clay as a gangue and containing both free and combined moisture,comprising, preliminarily heating the ore together with its ironcomponent and its gangue to drive off the free moisture, tumbling theore and gangue to break up the same, then subjecting the dried ore andgangue to a separate and com plete heating operation to drive off thecombined moisture, tumbling the ore and its gangue to loosen the ganguefrom the ore, and subjecting the ore and its gangue to a blast whichremoves the gangue from the ore.

2. The process of clearing ores, having iron as an economic component,having'clay as a gangue and containing both free and combined moisture,comprising preliminarily heating the ore together With its ironcomponent and gangue to drive 011' the free moisture, then subjectingthe ore and gangue to a separate heating operation to drive ed thecombined moisture, and separating the gangue from the ore.

- 3. The process of clearing ores having iron as an economic component,having clay as a gangue and containing both free and combined moisture,comprising, heating the ore' together with its iron component and gangueto drive off the free moisture, subecting the ore and gangue to aseparate heating operation to drive 011' the volatile matter, tumblingthe ore and gangue to loosen the gangue from the ore, and subject ingthe ore and gan e to a blast which separates the gangue mm the ore.

4. The process of clearing ores, having iron as an economic component,having clay as a gangue and containing both free and combined moisture,comprising, preliminarily and gradually heating the ore together withits iron component and its gangue to drive ofi the freemoisture,subjecting the ore and its gangue'to a separating heating operation todrive oif the combined moisture, tumbling the ore and itsgangue toloosen the'gangue from the ore, and subjecting the ore and its gangue toa blast which removes the gangue from the ore.

5. The process of clearing ore, having iron as an economic component, ofits gangue, comprising heating the ore together with its iron componentand its gangue, crushing the resultant ore and gangue, tumbling thecrushed ore and gangue to loosen thegangue from the ore, and subjectingthe ore and its angue to a blast which removes the gangue rom the ore.

6. The process of clearing ore, having iron as an economic component, ofits gangue,

comprising heating the ore together with its iron component and itsgangue, crushing the resultant ore and gangue, heating and tumbling thecrushed ore and gangue to loosen the gangue from the ore, and subjectingthe ore and its gangue to a blast which removes the gangue from the ore.

7. The process of clearing ore, having iron as an economic component, ofits gangue, comprising heating and tumbling the ore together With itsiron component and its gangue, crushing the resultant ore and gangue,heating and tumbling the crushed ore and gangue to loosen the ganguefrom the ore, and subjecting the ore and its gangue to a blast whichremoves the gangue from the ore. i

8. The process of clearing ore, having iron as an economic component, ofits gangue, comprising subjecting the ore together with its ironcomponent and its gangue to a drying heat, crushing the resultant oreand gangue, then subjecting the crushed ore and gangue to a calciningheat, and separating the gangue from the ore.

9. The process of clearing ore, having iron as an economic component, ofits gangue, comprising heating the ore together with its iron componentand its gangue, crushing the resultant material, screening the resultantmaterial, tumbling the oversize to loosen the gangue from the ore, andsubjecting the oversize to a blast which removes the gangue from theore.

10. The process of clearing ore, having iron. as an! economic'component,of its gangue, comprising heating the ore together with its ironcomponent and its gangue, crushing the resultant material, screeningthe'resultant material, heating and tumbling the'oversize to loosen thegangue from the ore, and subjecting the oversize to a blast whichremoves the gangue from the ore.

11. The process of clearing ore, having iron as an] economic component,of its gangue, comprising preliminarily heating the ore together withits iron component and gangue to drive 05 the free moisture, crushingthe ore and gangue, then subjecting the oreand gangue' to a separateheating operation to drive oti' the volatile matter, and separating thegangue'from the ore.

12. The process of clearing ore, having iron as an economic component,of its gangue, comprising heating the ore together with its ironcomponent and gangue to drive off the free moisture, crushing the oreand gangue, heating the ore and gangue to drive off the volatile matter,tumbling the ore and gangue to loosen the gangue from theore, andsubjecting the ore and gangue to a blast which separates the gangue fromthe ore.

18. The process of clearing ores, having iron as an economic component,having clay as a gangue and containing both free and combined moisture.comprising preliminarily and gradually heating the ore together with itsiron component and its gangue to drive 0d the free moisture, crushingthe ore and gangue so treated, heating the crushed ore and its gangue todrive off the combined moisture, tumbling the ore and its gangue toloosen the gangue from the ore,'and subjecting the ore and its gangue toa blast which removes the gangue from the ore.

lln testimony whereof We have hereunto afiixed our signatures in thepresence of these witnesses.

EDWARD F. GOL'IRA. THOMAS S. MAFFITT. JESSE D. DANA. Witnesses;

W. A. S'rrnn, P. C. MAFFI'IT.

ROBERT W. EltWlN. Witnesses:

HARRY Oar,

FRANK CAMPBELL.

